Hello, I wrote:
This doesn't look consistent (aside from the TX4939IDE_REG8/16
issue) -- mm_outsw_swap() calls cpu_to_le16() before writing
16-bit data but this code doesn't. So, either one of those should
be wrong...
Thanks, this code should be wrong. IDE_TFLAG_OUT_DATA is totally
untested...
Hum, not necessarily...
If the data register is BE, this should work correctly, if I don't
mistake (once you fix the data register's address).
Hmm... or ide_tf_load()/ide_tf_read() is broken for big endian MIPS ?
(and possibly SPARC etc.)
__ide_mm_writesw(port, &data, 1) should be used instead of writew()
for IDE_TFLAG_OUT_DATA?
Probably the code there relies on the writew() doing the necessary
byte swapping -- the same as ata_{in|out}_data() must be reying on
ins[wl]() and outs[wl]() to do that, as well as on
__ide_mm_reads[wl]() and __ide_mm_writes[wl]() -- which boil down to
reads[wl]() and writes[wl]() on MIPS.
What's not clear to me is why in MIPS read[wlq]() vs reads[wlq](),
write[wlq]() vs writes[wl], in[wlq]() vs ins[wlq](), and out[wlq]() vs
outs[wlq]() are using the different byte swapping: the single form
uses ioswab[wlq]() while the sting form uses __mem_ioswab[wlq]() --
and those are defined as one swapping bytes and the other not in
incluse/asm-mips/mach-generic/mangle-port.h. Cananybody shed some
light on this?
Oh, I think I understand: the "single" versions take/return the value
in host endian but the "string" version must treat the data as a stream
of bytes.
MBR, Sergei
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